Holy Trinity Church is a Provincial Heritage Property situated prominently on the banks of the Churchill River at the northern community of Stanley Mission. The property features a grand cathedral with a tall central nave and elaborate spire built in a Gothic Revival style that was constructed between 1854 and 1860.

The heritage value of Holy Trinity Anglican Church at Stanley Mission lies in its status as the oldest known, existing building in Saskatchewan. Constructed between 1854 and 1860 under the supervision of Reverend Robert Hunt, who founded the mission in 1850, the church was once the focal point of a vibrant missionary complex that included nearly 30 supporting buildings and a cemetery. 

Heritage value also resides in the building's impressive architecture, which reflects the Gothic Revival style that was popular with the Anglican Church in England during the nineteenth century. Standing in sharp contrast to the typical small churches in western Canada, Holy Trinity's massing is only one of its unique features. The steeple and spire reach an impressive 23 metres (76 feet) and the walls are pierced by 37 Gothic-style arched windows, which together contain over one thousand pieces of stained glass. While the hardware, stained glass windows, and interior wood features were shipped from England, the local Cree constructed much of the building using hand-sawn lumber from the surrounding area. The post-and-beam construction, mud-and-stone infill walls, and fieldstone foundation reflect their use of construction methods that were native to the West. 

Further heritage value lies in the long-standing and deeply-rooted relationship between Holy Trinity and the local First Nations community. Established by the Church Missionary Society of England, the purpose of the church and mission was to convert local residents, mainly First Nations peoples, to Christianity. Traditionally known by the local Cree as the "shooting up place" where hunters set out on their hunting trips, the church and mission grew quickly. It became a permanent settlement for many First Nations families over the years and has served their community continuously for over 150 years. Although the community has gradually shifted to the south side of the Churchill River, Holy Trinity Anglican Church continues to be of spiritual significance to the local people. With its commanding presence overlooking the Churchill River in the remote northern wilderness, Holy Trinity Church stands as a remarkable architectural achievement and a reminder of the once thriving mission there.

The church building underwent extensive rehabilitation and restoration work coordinated by Saskatchewan's Parks Service in conjunction with Parks Canada, which was completed in 1983. This included replacement of the foundation and other structural improvements as well as the repair of damaged siding and floor boards.

Sources: Province of Saskatchewan, Notice of Intention to Designate as Provincial Heritage Property under The Heritage Property Act, May 14, 1981. Province of Saskatchewan, Order to Designate as Provincial Heritage Property under The Heritage Property Act, August 26, 1981. Province of Saskatchewan, Order in Council 870/86, August 21, 1986.